1. Field of the Invention
The disclosure of the present application relates to an extension device on which a main device can be mounted. The disclosure of the present application relates to an information processing system including the main device and the extension device.
2. Description of the Background Art
In recent years, because of the background such as size reduction of main device terminals, the cases where main devices and extension devices are connected to each other when being used have increased. A method for stably connecting a main device and an extension device is required. A conventional extension device has a guide rib formed along the outer shape of a main device, retains the main device with the guide rib, and guides the main device to a connection location. However, in this method, regulations are required with respect to the shape of the main device, a type of a connected connector, and the like, and have a huge effect on the layout of the main device.
Japanese Laid-Open Patent Publication No. 10-98515 (Patent Literature 1) discloses, for example, as shown in FIG. 1 of this publication, a plurality of key grooves 2a provided on each of both side surfaces of a terminal 2 and projections 1a and 1b on a cradle 1 side which are urged by an elastic member so as to freely extend and retract in response to engagement with each side surface and the key grooves 2a of the terminal 2 and are provided such that the positions of the projections 1a and 1b correspond to the positions of the key grooves 2a when the terminal 2 is fixed to the cradle 1. The cradle 1 disclosed in Patent Literature 1 includes a thick portion and a thin portion due to a step provided in either of a front portion or a rear portion, the projection 1b provided on the thin side, among the projections 1a and 1b, is formed so as to have a circular cross-sectional shape, and the terminal 2 is pressed down toward the thin side with the circular projection 1b as a rotating axis when the terminal 2 is removed from the cradle 1.
The microfilm of Japanese Laid-Open Utility Model Publication No. 3-101056 (Japanese Utility Model Application No. 2-8744, Patent Literature 2) discloses, for example, as shown in FIG. 1 of this publication, a portable radio 1 and a holder 2 that retains the portable radio 1. In addition, Patent Literature 2 discloses, for example, as shown in FIG. 1 of this publication, a retention structure for the portable radio in which thin grooves 11 are formed in both side surfaces of the portable radio 1, a recess 12 is formed in a back surface of the portable radio 1, the holder 2 includes a fixed portion 22 fixed within an interior of a car or the like and a holding portion 21 tiltably connected to the fixed portion 22, the holding portion 21 is provided with projections 24 engaged with the thin grooves 11 in the portable radio 1, and an engagement body 30 fitted into the recess 12 is provided in the fixed portion 22 in a state of being urged by a spring 29.
However, in the configuration disclosed in Japanese Laid-Open Patent Publication No. 10-98515, when an option component such as a grip belt or a handle member is mounted on the terminal, the terminal cannot be mounted on the cradle. Thus, when the terminal on which the option component is mounted is mounted on the cradle, the option component has to be removed from the terminal, and this is very troublesome. In addition, the configuration disclosed in the microfilm of Japanese Laid-Open Utility Model Publication No. 3-101056 (Japanese Utility Model Application No. 2-8744) also has the same problem.